/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
#ifndef itkExpandWithZerosImageFilter_hxx
#define itkExpandWithZerosImageFilter_hxx

#include "itkExpandWithZerosImageFilter.h"
#include "itkImageScanlineIterator.h"
#include "itkImageRegionConstIteratorWithIndex.h"
#include "itkObjectFactory.h"
#include "itkNumericTraits.h"

namespace itk
{
/**
 * Default constructor
 */
template <typename TInputImage, typename TOutputImage>
ExpandWithZerosImageFilter<TInputImage, TOutputImage>::ExpandWithZerosImageFilter()
{
  // Set default factors to 1
  for (unsigned int j = 0; j < ImageDimension; j++)
  {
    m_ExpandFactors[j] = 1;
  }

  this->DynamicMultiThreadingOn();
}

/**
 * Standard "PrintSelf" method
 */
template <typename TInputImage, typename TOutputImage>
void
ExpandWithZerosImageFilter<TInputImage, TOutputImage>::PrintSelf(std::ostream & os, Indent indent) const
{
  Superclass::PrintSelf(os, indent);

  unsigned int j;
  os << indent << "ExpandFactors: [";
  for (j = 0; j < ImageDimension - 1; j++)
  {
    os << m_ExpandFactors[j] << ", ";
  }
  os << m_ExpandFactors[j] << "]" << std::endl;
}

/**
 * Set expand factors from a single unsigned int
 */
template <typename TInputImage, typename TOutputImage>
void
ExpandWithZerosImageFilter<TInputImage, TOutputImage>::SetExpandFactors(const unsigned int factor)
{
  unsigned int j;

  for (j = 0; j < ImageDimension; j++)
  {
    if (factor != m_ExpandFactors[j])
    {
      break;
    }
  }
  if (j < ImageDimension)
  {
    this->Modified();
    for (j = 0; j < ImageDimension; j++)
    {
      m_ExpandFactors[j] = factor;
      if (m_ExpandFactors[j] < 1)
      {
        m_ExpandFactors[j] = 1;
      }
    }
  }
}

/**
 * BeforeThreadedGenerateData
 */
template <typename TInputImage, typename TOutputImage>
void
ExpandWithZerosImageFilter<TInputImage, TOutputImage>::BeforeThreadedGenerateData()
{}

/**
 * ThreadedGenerateData
 */
template <typename TInputImage, typename TOutputImage>
void
ExpandWithZerosImageFilter<TInputImage, TOutputImage>::DynamicThreadedGenerateData(
  const OutputImageRegionType & outputRegionForThread)
{
  // Get the input and output pointers
  OutputImagePointer     outputPtr = this->GetOutput();
  const InputImageType * inputPtr = this->GetInput();

  // Iterator for walking the output
  using OutputIterator = ImageScanlineIterator<TOutputImage>;

  OutputIterator outIt(outputPtr, outputRegionForThread);

  // Report progress on a per scanline basis
  const SizeValueType size0 = outputRegionForThread.GetSize(0);
  if (size0 == 0)
  {
    return;
  }

  const typename OutputImageType::IndexType outputOriginIndex = outputPtr->GetLargestPossibleRegion().GetIndex();
  // Walk the output region, and interpolate the input image
  while (!outIt.IsAtEnd())
  {
    while (!outIt.IsAtEndOfLine())
    {
      const typename OutputImageType::IndexType outputIndex = outIt.GetIndex();
      bool                                      indexIsMultipleOfFactor(true);
      for (unsigned int j = 0; j < ImageDimension; j++)
      {
        // Check that index (normalized to start with zero) is multiple of ExpandFactors
        if ((outputIndex[j] - outputOriginIndex[j]) % m_ExpandFactors[j] != 0)
        {
          indexIsMultipleOfFactor = false;
          break;
        }
      }
      // Copy value from input if index is multiplo, or set it to zero otherwise.
      if (indexIsMultipleOfFactor)
      {
        // Determine the input pixel location associated with this output
        // pixel at the start of the scanline.
        //
        // Don't need to check for division by zero because the factors are
        // clamped to be minimum for 1.
        typename InputImageType::IndexType inputIndex;
        for (unsigned int j = 0; j < ImageDimension; j++)
        {
          inputIndex[j] = outputIndex[j] / m_ExpandFactors[j];
        }
        outIt.Set(static_cast<OutputPixelType>(inputPtr->GetPixel(inputIndex)));
      }
      else
      {
        outIt.Set(NumericTraits<OutputPixelType>::ZeroValue());
      }
      ++outIt;
    }

    outIt.NextLine();
  }
}

/**
 * GenerateInputRequesteRegion
 */
template <typename TInputImage, typename TOutputImage>
void
ExpandWithZerosImageFilter<TInputImage, TOutputImage>::GenerateInputRequestedRegion()
{
  // Call the superclass' implementation of this method
  Superclass::GenerateInputRequestedRegion();

  // Get pointers to the input and output
  InputImagePointer  inputPtr = const_cast<TInputImage *>(this->GetInput());
  OutputImagePointer outputPtr = this->GetOutput();

  if (!inputPtr || !outputPtr)
  {
    return;
  }

  // We need to compute the input requested region (size and start index)
  unsigned int                             i;
  const typename TOutputImage::SizeType &  outputRequestedRegionSize = outputPtr->GetRequestedRegion().GetSize();
  const typename TOutputImage::IndexType & outputRequestedRegionStartIndex = outputPtr->GetRequestedRegion().GetIndex();

  typename TInputImage::SizeType  inputRequestedRegionSize;
  typename TInputImage::IndexType inputRequestedRegionStartIndex;
  /**
   * inputRequestedSize = (outputRequestedSize / ExpandFactor) + 1)
   * The extra 1 above is to take care of edge effects when streaming.
   */
  for (i = 0; i < TInputImage::ImageDimension; i++)
  {
    inputRequestedRegionSize[i] = static_cast<SizeValueType>(
      std::ceil(static_cast<double>(outputRequestedRegionSize[i]) / static_cast<double>(m_ExpandFactors[i])) + 1);

    inputRequestedRegionStartIndex[i] = static_cast<SizeValueType>(
      std::floor(static_cast<double>(outputRequestedRegionStartIndex[i]) / static_cast<double>(m_ExpandFactors[i])));
  }

  typename TInputImage::RegionType inputRequestedRegion;
  inputRequestedRegion.SetSize(inputRequestedRegionSize);
  inputRequestedRegion.SetIndex(inputRequestedRegionStartIndex);

  // Make sure the requested region is within largest possible.
  inputRequestedRegion.Crop(inputPtr->GetLargestPossibleRegion());

  // Set the input requested region.
  inputPtr->SetRequestedRegion(inputRequestedRegion);
}

/**
 * GenerateOutputInformation
 */
template <typename TInputImage, typename TOutputImage>
void
ExpandWithZerosImageFilter<TInputImage, TOutputImage>::GenerateOutputInformation()
{
  // Call the superclass' implementation of this method
  Superclass::GenerateOutputInformation();

  // Get pointers to the input and output
  InputImagePointer  inputPtr = const_cast<TInputImage *>(this->GetInput());
  OutputImagePointer outputPtr = this->GetOutput();

  if (!inputPtr || !outputPtr)
  {
    return;
  }

  // We need to compute the output spacing, the output image size, and the
  // output image start index
  const typename TInputImage::SpacingType & inputSpacing = inputPtr->GetSpacing();
  const typename TInputImage::SizeType &    inputSize = inputPtr->GetLargestPossibleRegion().GetSize();
  const typename TInputImage::IndexType &   inputStartIndex = inputPtr->GetLargestPossibleRegion().GetIndex();
  const typename TInputImage::PointType &   inputOrigin = inputPtr->GetOrigin();

  typename TOutputImage::SpacingType outputSpacing;
  typename TOutputImage::SizeType    outputSize;
  typename TOutputImage::IndexType   outputStartIndex;
  typename TOutputImage::PointType   outputOrigin;

  typename TInputImage::SpacingType inputOriginShift;
  for (unsigned int i = 0; i < TOutputImage::ImageDimension; i++)
  {
    outputSpacing[i] = inputSpacing[i] / (float)m_ExpandFactors[i];
    outputSize[i] = inputSize[i] * (SizeValueType)m_ExpandFactors[i];
    outputStartIndex[i] = inputStartIndex[i] * (IndexValueType)m_ExpandFactors[i];
    const double fraction = static_cast<double>(m_ExpandFactors[i] - 1) / static_cast<double>(m_ExpandFactors[i]);
    inputOriginShift[i] = -(inputSpacing[i] / 2.0) * fraction;
  }

  const typename TInputImage::DirectionType inputDirection = inputPtr->GetDirection();
  const typename TOutputImage::SpacingType  outputOriginShift = inputDirection * inputOriginShift;

  outputOrigin = inputOrigin + outputOriginShift;

  outputPtr->SetSpacing(outputSpacing);
  outputPtr->SetOrigin(outputOrigin);

  typename TOutputImage::RegionType outputLargestPossibleRegion;
  outputLargestPossibleRegion.SetSize(outputSize);
  outputLargestPossibleRegion.SetIndex(outputStartIndex);

  outputPtr->SetLargestPossibleRegion(outputLargestPossibleRegion);
}
} // end namespace itk

#endif
